my dad has a 95 aero and all of a sudden the boost has just died, A while back he could hit boost cutoff under hard enough acceleration...and then found out he had a blown apc. Bought a used one and ever since hes been runnin what feels like much lower boost. We finally measured it yesterday off the vac take off...and found that hes only hitting 4.5-5 psi max. From my research he should be running upwards of 6-7. Do you think something is broken? or they sent him an apc from a model with more boost control? or something? were completly stumped at this point since everything seems to be in perfect running condition.....

:o 5.5 psi is the base boost approximately, so your dad's Aero is pretty much getting base boost only. Reasons for that can be numerous:
-Brake pedal switch sticking on (i.e. brake lights are lit even if the pedal is not pressed)
-Faulty APC solenoid or related wiring
-Vacuum leaks
-Faulty bypass/dump valve

and so on...

-Ville